During a telephone conversation one has the ability to activate auxiliary services such as call forwarding, conference calling, etc., which are initiated by sending the appropriate control signal to the service provider using a method such as pressing a button or combination of buttons on the telephone. In a telephone connected to a public switched telephone network (PSTN), the control signals are usually transmitted in the form of dual-tone multi-frequency (DTMF) audio signals over the same channel as the voice. The result is that the other party to the conversation can detect that a request for a service has been made, although he or she may not be able to detect which particular service has been requested.